The authority of emergency interim successors to succeed to the powers and duties of legislators shall expire two years following the inception of an attack, but nothing herein shall prevent the resumption before such time of the filling of legislative vacancies and the calling of elections for the General Assembly in accordance with applicable constitutional and statutory provisions. The Governor acting by proclamation, or the General Assembly, acting by concurrent resolution, may, from time to time, extend or restore such authority or the operation of any of such provisions upon a finding that events render the extension or restoration necessary, but no extension or restoration shall be for a period of more than one year.